LONDON (Reuters) - Foreign minister Boris Johnson was accused by a government statisticians of misusing state data after he repeated a pro-Leave campaign mantra that Britain would have an extra 350 million pounds a week after Brexit. The figure had been a central part of the campaign's "let's take back control" message, with suggestions that the money could instead be used to fund state healthcare. Johnson was one of the few prominent members of the campaign not to abandon the pledge after it won the summer 2016 referendum on EU membership. David Norgrove, of the UK Statistics Authority, said he was "surprised and disappointed" that Johnson was still quoting a figure that confused gross and net contributions. "It is a clear misuse of official statistics," Norgrove said in a letter to the minister on Sunday. He said the number quoted did not include the rebate that Britain receives from the EU, nor did it include payments from Brussels to support, for example, agriculture and scientific research. Johnson, whose carefully tussled blonde hair and apparent bumbling manner has made him one of Britain's most recognizable politicians, mentioned the figure again in a Saturday newspaper article that laid out his vision for post-Brexit Britain. "Once we have settled our accounts, we will take back control of roughly 350 million pounds ($476 million) a week," he wrote. "It would be a fine thing, as many of us have pointed out, if a lot of that money went on the NHS (National Health Service)." Johnson later added he was "surprised and disappointed" by Norgrove's letter, which he said "was based on what appeared to be a wilful distortion of the text of my article", according to the BBC. Britain had no control of EU spending in Britain or of a rebate that was part of a funding arrangement agreed with other EU states, Johnson said. Figures published by the Office for National Statistics in April 2016 showed Britain's weekly net contribution to the EU to be about 190 million pounds a week.